Stencil sheet assesfblx  and cushion



Jan. 31, 1956 c. L. w. BRANDT ET AL 2,732,795

STENCIL SHEET ASSEMBLY AND CUSHION SHEETS FOR USE IN SAME Filed Dec. 11, 1952 r 4, W M 4% United States Patent STENCIL SHEET Assnrusry AND ousnroN SHEETS non use In SAME Application December 11, 1952, Serial No. 325,367 5 Claims. c tor-128.2

This invention relates to an improvement in the art of stencilization and it relates more particularly to a new shth h ee f r se in St nci h et a em i t the ps qn an h c a act r s ic he of- Wi a sul ri e hse to seesaw s practiced in Q fie' W hv it a be n. foun d sira le t ma u e h u i n e t inte lea ed, etw e t s e c a d cki ss a s e cil .hee a m In h past, cushion sheets have. been formed of various fibers but bestuse has been made of tissue fabricated of such long fibers as Kozu fibers and the like. While st rifcilizatf'ion was improved by the use of such fibrous tissues, correction was difiicult' because the displaceable siencil coating composition caused the stencil to adhere to the cushion sheet and smudgirig very often occurred w t the resu a u ed and. ll i age i formed on the stencil which mahes readability and proofreadin mor difficult. I

' t' s a q ishit h t hvsh h to pro u and to provide a method for producing a new and, improved cush on. ee for u e st ncil hee =1 hh hr ih 'i' s t ha s har ristics heret f r xi ti n h' s O fibrb'ut tissue r sub an iall hmpl ly ehm ha sdv It s a h s o is t this iht hti h t cr h s d to provide a method for producing a cushion sheet for use in a stencil sheet assembly wherein write-off can be s tt tmth t kin h o ma in a i b e of the sitmcilized material.

It is a further object to produce a cushion sheet of the type described in which cut-out of the loop letters and cutting of the fibers in the stencil base sheet are minimized thereby to enable improved stencilization and the pi oduction of copy of good quality.

These and other objects and advantages of this inventibrr will hereinafter appear and for purposes of iln ration, but not of limitation, an embodiment of the invention is shown in the accompanying drawing in whichi Figure 1 is a perspective view of a stencil sheet asice the. openings to produce copy of good quality. The term write-off is meant to refer to the function of the Cushion sheet as a carbon sheet to reproduce thestencil openings as copy on the backing sheet.

When the top side of the base paper adjacent the stencil sheet is coated with a wax composition, sticking is" minimized but when, at the same time, a similar wax or oily coating is provided on the underside of the has: sheet for the purpose of giving writemfit onto backing sheet, as in a conventional carbon, excessive cutting of the, fibers of the stencil base tissue occurs during stencilization with the result that the loop letters are lost and a proper lattice-work of fibers is not available across the openings to control the ink flow for the productionpf copy of good; quality. It has been found that a coating in the form of an oil or a wax composition cannot be tolerated in amounts even as lowtas i pound per: 3OQQ square feet of surface on the underside of the cushion sheet without causing this undesirable amount of cutting of the stencil fibers.

In accordance with the practice of this inventiorhxthe difliculties heretofore encountered in the manufacture ofa cushionsheet 10 capable of good writeaotfonto the backing sheet 15 and decrease in the amount of fiber Qhtt-iha nudgin nd s k n are o ercome y the rication ef a cushion sheet. 10 having a wax coating 11 on the side of the base paper 12 adapted to underlie the stencil sheet 13 while the opposite surface of the base sheet is provided with dry pigment 14 rubbed or brushed into the surface to prevent smearing, coating on the p Side of the ushio hea i adapted t be pigmented to provide a contrastingv color, such as white for blue or green stencils or black for white stencils semblywhich makes use of a cushion sheet embodying fsttt' r i of hi en i n. n

b Figure 2 is an enlarged sectional elevational view of the cus ion; sheet shown in Figure. 1.

It has. been found that by application of wax coatings onto cushion sheetsof closed formation, e. g. ordinary waxing. stock, many of the problems heretofore described are substantially. completely eliminated, but a number of hop c e i p a e nd co tr th h of nk us whereby the visibility of' the stencil openings that are formed is greatly increased with'the result that the stencil is more easily readable;

The pigment which is incorporated without a carrier intqthe bottom side of the cushion sheet may comprise carbo black, lampblack, ph sphotungstate green, phthalocyan-rne blue, iron blue or the like. When applied in the dry state, the. pigment may be dusted onto the surface and then subbedor brushed with a cotton pad, cotton covered roller, bristle brush or the like, not only to remove the excess pigment from the surface but to intbed the remainder into the interstices between the fibers; to the end that a relatively high gtoss is: provided on the write-off; side of the cushion sheet. The pig ment is, adapted to be present in amounts of about 'i pound per 3QQO, square feet of surface area but may be: present in practice in amounts ranging from. am 3 pounds per; 3000 square. feet of surfacearea. After the excess is removed andf the remainderis. worked into the surfa c, the cushion sheet becomes relatively inca- Phhls Q m a ing Q 5 smttds s ut is, able to: pro c 89 d (tits- E Q t h acki she t A; pigmented iaths t o he ne soothed; wh ch, s: l n. t he tough and which has no displaceable color coating is believed to be new in the art of manifol cling sheets and particularly new in a cushion sheet of the type described, in; stead of dusting the dry pigment onto the surface of the sheet, it is preferred to apply the pigment from a dispersion in a solvent system such as in trichloroethylene or alcohol or from an aqueous dispersion followed by elimination ofthe carrier to leave the dry pi-gment'and removal, of, the, excess by rubbing and ,polishingjupon d'rr h r- As the wax coating on the side of the cushion sheet ad p ed. hndetlie e c h t v use m y e ma of natural waxes, coal tarwaxes, mineral waxesand; perh am. es of the yp pa afii w s. arnauhaw x q ohsr te; o sh y w x-,1 ahd illa as. p r la utn 5 h like l hs FiF4 iIll F r o l me hod cizers to impart the desired softness to the coating. It has been found that polyethylene and other hydrocarbon polymers in amounts up to about percent by weight .of the coating composition may be incorporated as an ingredient in the wax base to toughen the coating and to make it more suitable for the purpose for which it was intended and to prevent smudging and sticking to the .stencil.

Various pigments may be incorporated into the wax base to introduce the contrasting color whereby the' formed stencil becomes more readable. With light colored stencils, black pigments such as carbon black, lampblack and the like may be incorporated'and for dark blue or green stencils, the wax coating may be formulated to contain a white pigment such as titanium dioxide, lithopone, zinc oxide, lead oxide and the like. The amount of pigment or dye in the wax coating composition is not critical so long as a contracting color of sufficient intensity is developed.

In practice, the wax coating is applied onto the paper as by a roller coater in the form of a hot melt in Weights ranging from 8 to pounds per 3000 square feet of surface area. It is desirable to keep the wax coating from penetrating to the other side which is adapted to be treated with drypigment. i The following will represent practice of this invention in the manufacture of a white coated cushion for use with blue stencils (Example 1) and in the manufacture of a black coated cushion for light colored stencils (Example 2):

Example 1 Composition:

18.8 percent paraffin wax 7.6 percent carnauba wax 6.3 percent ouricury wax 9.7 percent candelilla wax 23.1 percent white petroleum 6.0 percent polyethylene resin. 28.5 percent titanium dioxide The coating composition is'applied by a roller coater or by other suitable coating means as a hot melt heated to a temperature of about 210 F. Application is made to provide a coating 10 onto one side of a base paper 11 in amounts ranging from 10 to 12 pounds per 3000 square feet of surface area.

Carbon black in amounts ranging from about 1 to 1% pounds per 3000 square feet is dusted onto the opposite side of the base paper 11 before or after application of the wax coating layer 10. The pigmented side is first engaged by a cotton covered roller to displace excess pigrnent and rub some of the pigment into the paper and it is then engaged by a series of rotating brushes which furtherremoves excess carbon black and imparts a fairly high finish to the pigmented side 12 of the cushion sheet.

A cushion sheet of the type described is adapted to be positioned in a stencil sheet assembly 13 with the coated side 10 adjacent the underside of a stencil sheet 14 and the pigmented side 12 adjacent the underlying backing sheet 15.

Example 2 Composition:

40 percent carnauba wax 40 percent dark petrolatum percent furnace black This composition is applied as a hot melt onto one side of a base paper to form a wax layer in amounts ranging from about 8 to 10 pounds per 3000 square feet of surface area.

Prior to application of the wax coating, the underside of the base paper is treated with phthalocyanine blue contained as a dispersion in trichloroethylene. After drying, the pigmented side is rubbed with a cotton pad and then burnished with a rotating bristle brush'whereby excess pigment is removed from the surface and the remainder is rubbed.

It will be apparent from this discussion that a new and improved cushion sheet for use in stencil sheet assemblies is provided wherein good write-off is secured during stencilization without cutting the fibers of the stencil base tissue and with the elimination of sticking between the stencil and the cushion sheet as well as elimination of smudging which has heretofore resulted in the production of stencils of poor readability.

It will be understood that changes may be made in the details of application and formulation of the various compositions applied to the base paper, tissue or other open fibrous sheet stock in the formation of the cushion sheet without departing from the spirit of the invention, especially as defined in the following claims.

We claim:

1. In a stencil sheet assembly having a backing sheet and a stencil sheet formed of a base tissue having an ink impervious displaceable coating, a cushion sheet interposed between the stencil sheet and the backing sheet, said cushion sheet comprising a base paper having a wax coating on the surface underlying the coated stencil and dry pigment free of any liquid carrier and vehicle rubbed into the surface adjacent the backing sheet.

2. In a stencil sheet assembly having a backing sheet and a stencil sheet formed of abase tissue having an ink impervious displaceable coating, a cushion sheet in- Y terposed between the stencil sheet and the backing sheet, said cushion sheet comprising a base paper having a wax coating on the surface underlying the coated stencil and containing a pigment in the wax coating to provide a contracting color with the stencil'sheet and dry pigment free of any liquid carrier and vehicle rubbed into the surface adjacent the backing sheet.

3. In a stencil sheet assembly having a backing sheet and a stencil sheet formed of a base tissue having an ink impervious displaceable coating on one surface thereof, a cushion sheet interposed between the stencil sheet and the backing sheet, said cushion sheet comprising a base paper having a wax coating pigmented to provide a contrasting color with the coated stencil on the surface of the base tissue underlying the coated stencil sheet and dry pigment free of any liquid carrier and vehicle in 1 amounts ranging from /2 to 3 pounds per 3,000 square feet of surface area imbedded into the surface of the base paper adjacent the backing sheet.

4. A cushion sheet for use in a stencil sheet assembly comprising a base paper, a pigmented wax coating on one side of the base tissue and dry pigment particles free of any liquid carrier and vehicle imbedded in the other side of the base tissue in amounts ranging from /2 to 3 pound of dry pigment for 3,000 square feet of surface area.

5. The method of producing a cushion sheet for use in a stencil sheet assembly comprising the steps of coating -oneside of a paper base sheet with a wax composition in a manner to prevent excessive penetration, coating the other side of the sheet with a pigment dispersed in a solvent system, removing the solvent to deposit the dry pigment on the coated side of the base sheet, and then brushing the pigment coated'base sheet to imbed the pigment particles in the base sheet and remove the excess thereof.

References Cited in the file of this patent. UNITED STATES PATENTS ng J 

1. IN A STENCIL SHEET ASSEMBLY HAVING A BACKING SHEET AND A STENCIL SHEET FORMED OF A BASE TISSUE HAVING AN INK IMPERVIOUS DISPLACEABLE COATING, A CUSHION SHEET INTERPOSED BETWEEN THE STENCIL SHEET AND THE BACKING SHEET, SAID CUSHION SHEET COMPRISING A BASE PAPER HAVING A WAX COATING ON THE SURFACE UNDERLYING THE COATED STENCIL AND DRY PIGMENT FREE OF ANY LIQUID CARRIER AND VEHICLE RUBBED INTO THE SURFACE ADJACENT THE BACKING SHEET. 